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Atlanta Regional Council (ARC), Atlanta, Georgia

Figure 2: The Three "Dimensions" of Congestion

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The three dimensions of congestion that ARC measures: intensity, duration, and extent. See below for more details.

Intensity

Intensity addresses the question "How bad does congestion get on a particular roadway?" The graphic shows a scale from minimal to severe and has a series of three-lane roadways segments. The first segment show only a few cars at the minimal end, increasing to a segment with all the lanes full of cars at the severe end.

Duration

Duration addresses the question "How long do congested conditions last on the roadway?" A graph shows traffic volume on the vertical axis and time of day on the horizontal axis. A horizontal line divides congested conditions from uncongested conditions. Two roadways are graphed: Road "A" has lower peaks in volume but with congested conditions for 9 hours a day, Road "B" has higher peaks but only 4 hours of congested conditions.

Extent

Extent addresses the question "From a regional perspective, how many people are impacted by congestion on the roadway?" The graphic shows a scale increasing from 'few' to 'many' with a series of congested roadway segments. At the 'few' end, it is a one-lane road and the number of lanes increases to six at the 'many' end.

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Updated: 07/25/2011
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